Preparation And Properties Of Crosslinkable Rare Earth / Polymer Protective Materials

Rare earth elements have excellent properties such as light,electricity and magnetism,and have strong complexation ability.They are easy to be compounded with polymers to prepare materials with excellent properties.At present,rare earth elements are widely used in many fields such as chemical industry,agriculture,national defense and so on,with broad development prospects.Polyurethane has radiation protection effect and radiation stability,so it is suitable to be used as the base material of protective material.In this paper,unsaturated carboxylic acid rare earth salt was compounded into electrospun fiber membrane by electrospinning technology.Based on the in-situ self polymerization mechanism,the electrospun membrane of polyunsaturated carboxylic acid rare earth / polyurethane was prepared.The structure and properties of the electrospun membrane were studied in detail.In this experiment,unsaturated carboxylic acid was used to modify lanthanum and ytterbium,and the corresponding unsaturated carboxylic acid rare earth salt was prepared.The experimental results show that the particle size of the unsaturated carboxylic acid rare earth salt prepared by the acid-base reaction method is smaller than that by the direct reaction method,and the surface morphology is more regular,showing a needle shape,with a diameter of about 10-20μ m;however,under the same preparation method,rare earth methacrylate is easier to form a regular needle shape than rare earth acrylate salt,and the diameter is smaller.The spinning process of polyurethane fiber membrane was discussed.It was found that rare earth salt could improve its spinnability.The final spinning conditions are as follows:Polyurethane concentration 25 wt%,voltage 20 k V,receiving distance 12 cm,advance speed 0.5m L / h,roll speed 300 rad / min.DCP was used as crosslinking agent to heat treat the modified rare earth / polyurethane electrospun film under different conditions.The effects of heat treatment conditions and the amount of crosslinking agent on the microstructure of the composite film were investigated.The results of differential scanning calorimetry(DSC),infrared spectroscopy(FTIR)and scanning electron microscopy(SEM)show that the unsaturated carboxylic acid rare earth salt will cross-linking when heated,forming oligomers with different degree of cross-linking.The results of DSC,FTIR and SEM showed that the heat treatment temperature was 80 ℃,the heat treatment time was 3h and the amount of crosslinker was0.5g(dissolve in 10 m L DMF).The morphology of the fiber film was further characterized by TEM.It was found that the oligomer of rare earth salt of unsaturated carboxylic acid was more evenly dispersed in the polyurethane matrix,and its size was about 500 nm.Combined with EDS analysis,it is proved that rare earth elements are indeed dispersed in polyurethane matrix,and the dispersion is more uniform.The tensile strength of pure polyurethane electrospun film is low,and the mechanical properties of the film are obviously improved after the introduction of unsaturated carboxylic acid rare earth salt.With the increase of rare earth salt content,the tensile strength first increases and then decreases,but it is superior to the mechanical properties of pure polyurethane.After heat treatment,the tensile strength is further improved,up to 1700% of that of pure polyurethane electrospun film,and the mechanical properties of polyurethane electrospun film are increased The strong effect is very outstanding.Ytterbium methacrylate with the same content has stronger reinforcing effect than lanthanum methacrylate,and the electrospun film fiber has smaller diameter and more regular structure.